Project Summary Gestational Diabetes (or GDM) occurs in ~8% of pregnant women in the United States. Among women with GDM, 50% will develop subsequent Type 2 diabetes; these women have a 3-fold risk of developing cardiovascular disease (CVD). It is uncertain whether the severity of GDM is related to elevations in CVD risk factors. We hypothesize that more severe forms of GDM (according to dietary and/or pharmacologic treatment of her GDM, or higher Z score on 3-hour glucose from oral glucose tolerance testing) are related to elevations in traditional (blood pressure, lipids, diabetes) and/or novel (inflammatory markers, Lp(a) and atherogenic lipid subparticle size/number), CVD risk factors and/or elevated atherosclerotic CVD risk profile at ten years post- delivery. Current American College of Obstetrics and Gynecology guidelines recommend that women with GDM be screened 6-12 weeks postpartum for glucose intolerance. However, the effect of glucose intolerance at 1 or 2 years postpartum on CVD risk factors has not been studied. We hypothesize that early and persistent glucose intolerance from early to late postpartum will most strongly relate to high levels of traditional and novel CVD risk factors ten years after delivery. Finally, prior studies demonstrate that prevalent lifestyle factors of healthy diet and exercise may lower the CVD risk among women with GDM. However, the timing and persistence of healthy dietary and exercise changes in relation to established and novel CVD risk factors among women with GDM has not been studied. In addition, the extent to which poor sleep habits and sleep disruptions contribute to a higher burden of CVD risk factors at 10 years post-delivery are still poorly understood. We hypothesize that early and persistent adverse lifestyle factors (diet, exercise and sleep) will be associated with elevated CVD risk at ~10 years post-delivery. We will carry out study aims in the SWIFT Study- a prospective, cohort of mothers diagnosed with GDM (n=1,035, 31% Hispanic, 24% White, 13% Chinese, 11% South Asian, 12% Southeast Asian, 8% Black) who delivered at a Kaiser Permanente Northern California (KPNC) hospital (2008-2011). Women enrolled into SWIFT Study at 6-9 weeks postpartum (baseline) and attended 3 in-person annual research exams from baseline through two years later. We now leverage the SWIFT cohort rich databases and Biobank to measure blood pressure, lipids and assay novel biomarkers during the 10 year follow-up exam (2019-2021; projected n=800). A better understanding of precisely which women with GDM will develop elevated mid-life CVD factors will help us tailor primordial and primary CVD prevention. Our study aims will allow us to test hypotheses that (1) GDM phenotype severity, (2) longitudinal changes in glucose tolerance (from early to late postpartum) and (3) longitudinal changes in lifestyle factors/sleep disorders will precisely identify which women with GDM will develop the most adverse CVD risk profiles at 10 years post-delivery.